DESCRIPTION: (Adapted from the application) Stress is thought to contribute to a wide variety of human diseases, including the cardiovascular disorders of hypertension, cardiac arrhythmia, myocardial infarction and sudden death. Relatively little is known of the functional interactions and pharmacological mechanisms affecting synaptic transmission among the forebrain areas involved in generating and integrating the cardiovascular responses to environmental and emotional stress. The proposed studies will address the hypothesis that excitatory amino acid (EAA) receptor-mediated synaptic transmission in distinct nuclei within the amygdala, hypothalamus and periaqueductal gray plays an important role in mediating integrated cardiovascular responses to stress. Conscious rats chronically instrumented for the measurement of arterial pressure, heart rate, regional blood flows and for central administration of drugs will be used to address the following specific aims: 1) examine the role of EAA receptors at sites in the hypothalamus and periaqueductal gray in mediating the cardiovascular changes resulting from activation of the amygdala, 2) examine the role of EAA receptors at sites in the amygdala, hypothalamus and periaqueductal gray in mediating the cardiovascular changes resulting from activation of the dorsomedial hypothalamus, and 3) investigate the role of EAA receptors at sites in the amygdala, hypothalamus and periaqueductal gray in mediating the cardiovascular changes resulting from acute episodes of stress.